Method for producing mottled sheet material



Oct. 13, 1959 R. w. SNYDER 2,908,042

METHOD FOR PRODUCING MOTTLED SHEET MATERIAL Filegl DBG.- 21, 1955INVENTOR ROBERT W. SNYDER ATTORNEY Patented Oct. 1 3, 1959 METHOD FORPRODUCING MOTTLED SHEET MATERIAL Robert W. Snyder, Lititz, Pa., assignorto Armstrong Cork Company, Lancaster, Pa., a corporation of PennsylvaniaApplication December 21, '1955, Serial No. 554,585 3 Claims. 01. 1848.8

This invention relates to a method for producing a continuous sheet ofresilient material such as floor and wall covering. More particularly,this invention relates to a method for making a continuous sheet ofresilient material having a nondirectional design.

In the manufacture of resilient floor and wall coverings, it has beencommon practice to produce certain pattern design effects on calenderequipment. These design eflfects have certain definite limitations dueto the extrusion effect produced by the intense pressures exerted on thecolor particles as they are drawn into and pass through the nip of thecalender. Because of this extrusion elfect, all the pattern designsdeveloped for manufacture on calender equipment must, of necessity,include elements of a design elongated in the machine direction of thesheet material. An example of this is the jaspe pattern elfect wellknownin the resilient floor covering industry. This is produced from abackground color composition having uniformly dispersed therethrough aplurality of color particles of a shade different from the backgroundcomposition. The color particles so prepared are fed into the nip of asheeting calender, and the extrusion effect produced on the colorcomposition by the calender pressure draws the color particles into moreor less elongated lines in the finished sheet.

A great many of the highly desirable pattern design eifects in theresilient flooring industry today do not include design elements whichcan utilize this drawn-out extrusion effect. Typical of the designeffects which cannot be produced on calender equipment is the well-knownSpatter design, in which a plurality of spots of color composition arearranged in a background of a blending color. In a design of this type,any extrusion or elongation of the color particles is highlyobjectionable in that it destroys the character of the design. In orderto produce designs of the Spatter type, it is necessary to resort to themolding process of making sheet material. In

this molding process, the loose color composition is placed on a backingtraveling on a horizontal plane and is consolidated by means of aflat-bed press which consolidates the color particles to one another andadheres the mass to the backing. In the molding operation, the quantityof granular material placed on the backing is sufiicient to form a solidcompacted sheet, but it is carefully controlled to prevent the presenceof an excess of granular material in any given area of the sheet. Withthis close control of the quantity of material pressed on the backing,there is no possibility of extrusion resulting from the flat pressingoperation. However, it will be understood by those skilled in the artthat the molding operation is considerably slower than the calenderingoperation. The main'diiference being that by reason of the pressingoperation, the molding production must be carried on in intermittentsteps while the calendering operation is a continuous one and its speedis, therefore, considerably in excess of that of the molding operation.

, .For many years, the industry has been experimenting with apparatusfor and methods of producing nondirectional designs on conventionalcalender equipment, and such attempts have resulted in methods which areimpractical from a production standpoint because of the careful controlrequired in feeding the color composition to the calender. The inventionhere under consideration has been developed to enable the controlledfeeding of material to a calender operating at conventional calenderspeeds.

It is an object of this invention to provide a method for producingflexible sheet material having a nondirectional design on a calender atspeeds substantially in excess of those heretofore attainable only fordesigns having directional design effects.

It is another object of this invention to provide a process utilizing adevice for controlling the feed of granular color composition to asheeting calender so that sufficient material is supplied to form asolid unitary sheet with no excess to cause extrusion.

It is a further'object of this invention to provide a process forproducing a sheet of resilient decorative floor and wall covering havinga nondirectional design which can be reproduced on calender equipment.

In order that my invention may be more readily understood, it will bedescribed in connection with the attached drawing, in which:

Figure 1 is an elevational view of a two-roll calender with one rollremoved to more clearly illustrate the invention; and

Figure 2 is a cross sectional view of a two-roll calender including theinvention.

Referring to the drawing, there is shown a calender 2 having a backingroll 3 and a facing roll 4. The direction of rotation of the calenderrolls 3 and 4 is designated by the arrows. A plate 5 is provided inassociation with the facing roll 4. The positioning of the plate 5 issuch that the surface 6, which is hollow ground to conform to thecircumference of the facing roll 4, extends down toward the nip betweenthe two calender rolls in such manner as to prevent the loose colorparticles fed from a bank positioned between the backing roll 3 and theplate 5 from coming in contact with the facing roll 4 until they passthe point 7 on the edge of the hollow ground plate 5. This edge 7 ispositioned a predetermined distance above the narrowest point of thenip.

The extrusion effect which occurs ordinarily in the calenderingoperation of plastic material is caused by the pull-in eifect of the twocalender rolls working in co operation with one another on the loose mixmoving from the hopper into the nip. This pull-in effect draws morecomposition into the nip than is required to form a solid sheet. Theexcess material in the nip causes the finished this observation that theextrusion obtained in previous calendering operations is caused by thepull-in effect produced by the two calender rolls operating incooperation with one another to supply a greater amount of material tothe calender than is necessary to form a solid sheet.

By keeping the loose color particles away from one roll until the supplyof composition has been controlled to such an extent that onlysuflicient granular material is engaged by the two rolls to form a solidsheet and no more, this extrusion eifect is practically eliminated, atleast to the point where it is no longer objectionable. It is obviousfrom this that in the sheet formed by this method the extrusion of thecolor particles is substantially 3 eliminated, not only on the surfaceforming the decora tive wear layer of the material, but throughout theentire sheet; and the uniform configuration of the particles will bepresent throughout the sheet, resulting in a design which will be thesame in worn traffic lanes as well as in other areas.

In the formation of sheet material on a device of this type, it isnecessary that the color particles be supplied to the. nip of thecalender in sufficient quantity and under sufiicient pressure to beconsolidated into a solid unitary sheet with no voids. This problem doesnot arise in the conventional calendering operation by reason of theabove-mentioned pull-in effect, which insures that color composition issupplied to the calender in sufficient quantity to form a uniformlyconsolidated sheet.

Since in the device here under consideration the pullin effect isVirtually eliminated or greatly diminished, means must be provided toinsure supplying the color composition to the nip of the calenderuniformly and in a quantity sufficient to form a uniformly compactedsolid sheet. It has been found that by imparting motion to the colorparticles at the point where they come in contact with both calenderrolls, the necessary consolidating effect on the particles is obtainedand the sheet produced has substantially the same densitycharacteristics as the sheet produced on conventional calenderingequipment by reason of the fact that only suthcient color composition issupplied but no excess. This can readily be accomplished by impartingoscillatory motion to the plate 5. In determining the direction of themotion to be im parted to the plate 5, several important factors must beconsidered. It is essential if a uniform configuration of nondirectionaldesign is to be produced that the distance between the point 7 on thesurface 6 of the plate and the nip between the rolls remain constant.This means that in producing nondirectional design effects, it isdesirable to oscillate the plate 5 in a direction parallel to thelongitudinal axis of the calender roll 5} with which the plate 5 is inconstant engagement. This movement of the plate introduces the particlesinto the nip in proper compacted form to form a solid sheet, and thecolor particles forming the face of the sheet do not contact the rolluntil they pass the edge 7, and the distance between the edge 7 and thenip will always remain the same.

The horizontal oscillatory motion referred to in this preferredembodiment of the invention is imparted to the plate 5 by means of motor8 mounted on platform 9 built on the stationary framework 1 3 of thecalender proper. The plate is mounted on an inverted L-shaped mount ll,one section 12 of the L-shaped mount ill being disposed on a verticalplane and the other section 13 being disposed on a horizontal plane. Themotor 8 is provided with an eccentric 14 to which is connected a link15. he L-shaped mount 11 is provided with an extension 16. One end ofthe link 15 is attached to the eccentric l4- and the other end isattached to the extension 16.

The l.-sh:aped mount 11 is supported on hangers 17 which carry rollers18 on which the L-shaped mount ll moves. Guide rollers 19 are alsoprovided on the framework above the L-shaped mount ll to keep the mount11 on an even horizontal plane.

By utilizing the invention here under consideration, it may be possibleto create design elfects having a greater degree of extrusion in certainareas than in other areas. This can be accomplished by providing aserrated surface 6 on the plate 5. Gther unique design effects can heproduced by imparting reciprocatory movement to the plate in such manneras to alter the distance between the edge '7 of the plate and the nipbetween the rolls. This can be accomplished by moving the plate in adirection normal to the longitudinal axis of the calender rolls, or atany angle ranging between a direction normal to the axis of the rollsand parallel to the rolls.

The proper distance between the nip and the edge '7 is determined byseveral factors, the most important of which is the size of the colorparticles being used and the gauge or thickness of the material beingproduced on the calender. Of course, the thickness of the material isgoverned by the distance between the two calender rolls at their closestpoint. The diameter of the calender rolls is another important factor indetermining the proper positioning of the edge 7 with respect to thenip. Formulation also has an effect on this determination, inasmuch assome compositions, such as the newer vinyl type plastics, have differentcalendering characteristics from the conventional linoleum and asphalttile compositions and, therefore, the positioning of the plate fordifferent formulations may vary. All of these variables are within thescope of knowledge of the person skilled in the art. It is, therefore, arelatively easy matter to determine the proper position of the plate fora given set of conditions.

As a typical example, taking a conventional linoleum composition, thesize of the color particles used to produce the Spatter effect arewithin a range of Vs" to in diameter, and the color particles which formthe background of the composition are or less. In calendering a sheet ofmaterial .075 thick on a calender having 20 diameter rolls, the edge 7of the plate 5 should be positioned about 2 from the nip between thecalender rolls and the degree of movement of the plate in a horizontaldirection parallel to the longitudinal axis of the calender rolls shouldbe approximately 1". The above figures are given by way of example toshow the approximate positioning of the plate for a conventionallinoleum composition, and it will be understood that other positioningcan be determined by one skilled in the art familiar with thecomposition being utilized. It is important that the distance betweenthe edge of the plate and the opposite roll be greater than the size ofthe color particles being fed to the calender.

Because of the size of the plate, it has been found desirable to havethe advantage of the reinforcing effect of the roll in engagement withthe edge of the plate. In order to do this, the edge of the plate ishollow ground to conform to the shape of the roll so that the pressurecaused by the bank of color particles urges the plate into engagementwith the roll. It is not necessary so far as the invention 'is concernedto have the edge of the plate conform to the configuration of the roll;however, it has been found highly desirable to do so in order to keepthe plate rigid and also the edge 7 will wear uniformly. Due to the factthat calender rolls are rather expensive to manufacture, it ispreferable to have the plate 5 made of a metal which is softer than themetal of the calendar rolls so that any wear will be on the edge of theplate which can be replaced and the calender roll will not be marred.

When the larger color particles are used, it may be found desirable tomove the plate further away from the nip in order to enable more of theparticles to be compacted into the nip to form a unitary sheet. This canbe determined by one skilled in the art in carrying out the invention.

With the method here under consideration, it is possible to produce asheet of material having pattern design characteristics similar to thedesigns currently reproduced by the molded process and sold under suchtrademarks as Spatter and Granette. These designs have a background ofmaterial with contrasting color compositions disposed therein in suchmanner as to give a polka dot effect without the extrusion effectcurrently encountered by calendering operations. It is highly desirableto carry out this method on a calender, inasmuch as the granularcomposition can be rapidly fed to the calender in the formation of acontinuous sheet and there is no uniform repeat of the design. Thedesign is uniform throughout the entire sheet. Another advantage, ofcourse, is the speed of manufacture which introduces economies into themanufacture of sheet material, making it more desirable to thepurchasing public from an economic standpoint.

I claim:

1. In a method of calenderin'g mottled sheet material from a bank of amottled mixture of color particles disposed above the nip of aconsolidating sheeting calender, the steps comprising supplying fromsaid bank to the nip between the calender rolls, only sufficient colorparticles to form a compacted sheet in said nip, and oscillating saidcolor particles immediately above said nip by the application ofoscillatory motion thereto in a direction parallel to the longitudinalaxis of the calender rolls.

2. Ina method of calendering mottled sheet material from a bank of amottled mixture of granular color particles disposed above the nip of aconsolidating sheeting calender, the steps comprising supplying fromsaid bank to the nip of the sheeting calender rolls only sufficientgranular color particles to form a compacted sheet in said nip, the sizeof said granular color particles being smaller than the distance betweenthe calender rolls at the tip, and oscillating said granular colorparticles. immediately above said nip by the application of oscillatorymotion thereto in a direction parallel to the longitudinal axis of thecalender rolls.

3. In a method of calendering mottled sheet material, the stepscomprising supplying a limited quantity of a mottled mixture of granularcolor particles to the nip between the pair of calender rolls from abank of a mottled mixture of color particles maintained in the areadefined by one of the calender rolls and a barrier engaging the othercalender roll at a location spaced from the nip, applying oscillatorymotion to the particles by oscillating the barrier in a directionparallel to the longitudinal axis of the calender rolls.

References Cited in the file of this patent UNITED STATES PATENTS1,454,939 Michaelsen May 15, 1923 2,043,938 Thies June 9, 1936 2,374,496Perry Apr. 24, 1945 2,397,936 Glidden et al. Apr. 9, 1946 2,534,296 Pikeet al. Dec. 19, 1950 2,624,068 Dobry Jan. 6, 1953 2,642,371 Fahrni June16, 1953 2,758,336 Franssen Aug. 14, 1956 2,760,229 Cheney et al. Aug.28, 1956 FOREIGN PATENTS 524,140 Belgium May 10, 1954 929,754 GermanyJuly 4, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 2,908,042 October 13, 195,

Robert W.a Snyder It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionand that the said Letters Patent should readas corrected below.

Column 5, line 23, for "tip" read nip '"'0 Signed and sealed this 5thday of April 1960.

(SEAL) Attest:

KARL H. AXLINE ROBERT c. WATSON Attesting Officer Commissioner ofPatents

